Two reviewers provided constructive comments and recommendations for the publication. The reviewers gave positive comments about the value of the data and the interesting interpretations. Queries around use of 2 specific for isotope work have been addressed in the author replies, including clarifying that the isotope data is not ‘species-specific’. Further concerns about citing contextual information for the area has been addressed, as well as those related to the processes being explored with the simple model.

Further comments for the authors to consider are as follows:
1) Links between what is happening in the Benguela upwelling system and in the Southern Ocean, the source of the DSi. At present the data and it’s interpretation are presented without reference to knowledge of any changes in SO circulation / productivity, which may offer support or explanation to the patterns the authors propose. It may be that such data does not exist (e.g. at the resolution the authors work here) but the text in section 3.1 is very focussed only on the Benguela system, e.g.
o lines 174-175 notes “a decrease in the DSi concentration of the supplied water...”: is there data from the Southern Ocean marine archives which could predict/explain why this would happen or is it a signal driven by the local (upwelling) circulation changing? Do other Benguela sites offer support/explanation?
o line 183-184: as for my previous comment, are there other data sets which support or explain why this supply changed?
2) lines 66-67: since there has been a revision to the radiocalibration curves since the McKay et al. 2016 publication could the authors please clarify here which calibration model was used to generate the calendar ages? (rather than the reader having to seek out the original age model papers)
3) response to R1 regarding SST and upwelling: “reduced SST reconstructions” could be read as “fewer SST data points”. “...reduced SSTs as reconstructed from alkenone archives” might be more clear? The authors may also consider line 160-161: “Cooler SSTs indicate a pulse of upwelling...”?
4) response to R2 regarding Fe fertilisation: the authors note an addition on Line 205 to address this concern. Although this addition refers to ‘dust supply’ it does not indicate whether this refers to the concern about Fe fertilisation which was expressed by the reviewer. Could the authors consider clarifying here if they are arguing for a lack of Fe fertilisation when they refer to dust, or are they referring to DSi and/or Fe supply?

I ask that the authors address these comments alongside their replies to the reviewers, and incorporate all of their suggested corrections into a revised version of their manuscript for further consideration.